How deep should service entrance cable be buried?

[Caulki...@work.com]

I need to run some underground service entrance cable to a building from
a power pole. This is a farm, where the pole has a main breaker, and
sub breakers that go to different buildings, (mostly all overhead
triplex).

Anyhow, because of trees and other obstacles using overhead wiring is
not possible. (Not to mention more costly, since an extra power pole
would need to be installed). So, underground appears to be the way to
go. It will be a cable made for underground use, and supply 100A, using
#2 AL 3 wire plus ground cable.

I dont have a code book handy. I need to know the proper depth (minimum
required depth) to place that cable. This will be under a lawn, which
may be driven over by a farm tractor occasionaly.

Anyone have a code book handy?

By the way, is there any website that has the entire electrical code
book online? It seems that I recall someone saying something about that
in the past.

[Dean Hoffman]

On 11/7/13 5:19 AM, Caulki...@work.com wrote:
> I need to run some underground service entrance cable to a building from
> a power pole. This is a farm, where the pole has a main breaker, and
> sub breakers that go to different buildings, (mostly all overhead
> triplex).
>
> Anyhow, because of trees and other obstacles using overhead wiring is
> not possible. (Not to mention more costly, since an extra power pole
> would need to be installed). So, underground appears to be the way to
> go. It will be a cable made for underground use, and supply 100A, using
> #2 AL 3 wire plus ground cable.
>
> I dont have a code book handy. I need to know the proper depth (minimum
> required depth) to place that cable. This will be under a lawn, which
> may be driven over by a farm tractor occasionaly.
>
> Anyone have a code book handy?

The wire needs to be two feet deep. The conduit should extend
into the ground 18". PVC conduit (schedule 80) needs either a bell end
or bushing at the bottom end. One of the local electricians tamps
the ground a bit around the bottom of the conduit. His theory is mice
are less likely to get into the conduit. They supposedly encounter the
packed earth then quit digging.

[John Grabowski]

*As Dean said, Table 300.5 specifies 24". I recommend installing a warning
ribbon a few inches below the surface of the lawn to avoid potential damage
in the future from digging.

[Ed Pawlowski]

On 11/7/2013 6:19 AM, Caulki...@work.com wrote:

> I dont have a code book handy. I need to know the proper depth (minimum
> required depth) to place that cable. This will be under a lawn, which
> may be driven over by a farm tractor occasionaly.
>
> Anyone have a code book handy?

I think the code is 24" but I'd not bet money on that. What is
important, are you going to have a permit and inspection? Then it
should be as deep as the local inspector thinks it should be.

[jamesgang]

I concur with the 2ft. Personally I'd bag the aluminum and go copper but I'm not handing over the money to buy the cable so I understand the aluminum :-)

[TomR]

Here's a link to a free copy of the 2011 NEC:

http://www.town.belmont.ma.us/Public_Documents/BelmontMA_CommDev/National%20Electrical%20Code%202011.pdf .



There is a newer version (2014), and you can free access to that online, but
you have to create a free online account to view it. Here's the link:



http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70

[Dean Hoffman]

On 11/7/13 9:13 AM, gfre...@aol.com wrote:

> On Thu, 7 Nov 2013 07:41:19 -0500, "John Grabowski"
> <jgra...@optonline.net> wrote:
>

>> *As Dean said, Table 300.5 specifies 24". I recommend installing a warning
>> ribbon a few inches below the surface of the lawn to avoid potential damage
>> in the future from digging.
>

> In fact 300.5(C)(3) requires the ribbon
>
> (3) Service Conductors. Underground service conductors that are not
> encased in concrete and that are buried 450 mm (18 in.) or more below
> grade shall have their location identified by a warning ribbon that is
> placed in the trench at least 300 mm (12 in.) above the underground
> installation.
>

Had to cut some of original post due to AIOE quotation limit.
I wonder if there will be circuit breakers on the pole actually
feeding this particular circuit. If so, would that negate the code
requirement for the warning ribbon?

[Caulki...@work.com]

Yes to the breaker!